1. Field of the Invention
The present invention relates generally to building structure materials, and more specifically to an infiltration barrier used in building construction to improve energy efficiency and to protect against air infiltration and moisture build-up in buildings.
2. Description of Related Art
In order to improve the energy efficiency of new and existing buildings, it has been common practice in building new structures, and in residing old structures, to cover the exterior wall sheathing with an infiltration barrier, for example, prior to installation of a covering material such as siding. One such infiltration barrier is a high density polyethylene fiber sheeting. While infiltration barriers cut down on drafts and thereby convective heat loss, they provide little other contribution to the energy efficiency of the structure.
In addition to addressing energy efficiencies of new and existing buildings, moisture concerns can be one of the worst enemies of home or building construction. Water or moisture or humid air infiltration if allowed to penetrate behind siding or brick can saturate the wood of a building structure, thereby creating an environment that encourages mildew or rot. A weather resistant barrier has for many years been applied to the wood studs of buildings and homes in order to resist the moisture or water generated by weather. Such material is typically flexible and in a film or sheet form. Typically, this weather resistant barrier or “house wrap” is applied to the wooden stud frame before the application of a final siding or veneer (e.g. brick, metal, painted wood). Many such “wrap” products are commercially available such as, for example: Dupont Tyvek®, Typar®. Housewrap (www.typarhousewrap.com), and Barricade®, building wrap (www.ludlowcp.com).
In 2010 the International Energy Conservation Code (IECC) and International Residential Code (IRC) increased the thermal performance requirements for residential walls. Both of these standards seek to improve thermal performance and reduce energy needs per dwelling. As of January 2010 the U-value requirement for geographical area or zones 5-8 is 0.057; the reciprocal R-value for wall systems is R-20. The U-factor is the inverse, or reciprocal, of the total R-Value, i.e.: U-factor=1/Total R-Value. The R-Value is the thermal resistance to heat flow. A larger R-Value means that the material has greater thermal resistance and more insulating ability as compared to a smaller R-Value. Such R-Values can be added together. For instance, for homogeneous assemblies, the total R-Value of an insulation assembly is the sum of the R-Value of each layer of insulation. These layers may include sheathing and finishes, the insulation itself, air films and weatherproofing elements.
In order to meet the new building requirements, builders have employed additional building techniques such as altering construction of framed openings. For example, typically, builders have constructed walls on 2×4 framing. However, due to the revised requirements, builders are altering building designs by constructing walls on 2×6 framing and inserting, for example, R-20 mass insulation within the respective wall cavity in order to meet the energy/code regulations mandated within the building industry. These techniques, however, increase construction costs because of the added and more expensive construction materials. In addition, the increased size of framing also produces a loss in living space. Nevertheless, many builders have simply accepted the added cost and loss of living space created by the newly implemented thermal code changes.
Accordingly, a need exists for providing a protective wrap that improves energy efficiency and protection against air infiltration and moisture build-up in buildings while satisfying newly implemented industry-wide energy/code regulations. There is also a need for employing a protective wrap which meets or exceeds the newly implemented code requirements on existing framing structures or openings and/or without increasing the wall profile of a building.